I bet you don't see this article quoted in the mainstream newsmedia. I don't want to go on record as saying that man-made pollution has no effect on the environment. I am sure it does. But, I think it is not the primary reason the earth is warming. My favorite parts:
The findings prove that the world experienced a Medieval Warm Period between the ninth and 14th centuries with global temperatures significantly higher even than today.
They also confirm claims that a Little Ice Age set in around 1300, during which the world cooled dramatically. Since 1900, the world has begun to warm up again – but has still to reach the balmy temperatures of the Middle Ages.
The timing of the end of the Little Ice Age is especially significant, as it implies that the records used by climate scientists date from a time when the Earth was relatively cold, thereby exaggerating the significance of today's temperature rise.
When I was at the Smithsonian last summer, there was an exhibit that addressed the "recent global cooling trend." I guess the Smithsonian is a part of the vast right wing conspiracy too.